Three-dimensional percolation effect on electrical conductivity in films of metal nanoparticles linked by organic molecules

Abstract

We study experimentally and theoretically the electrical conductivity of films made of gold nanoparticles linked by alkanedithiol molecules. The dependence of the conductivity on the length of the alkanedithiol molecule and on the thickness of the nanoparticle films at room temperature is investigated. We describe theoretically conductance between adjacent metal nanoparticles in terms of single electron tunneling along the linker molecules. Due to variations in the separation gaps between neighboring nanoparticles a film can be approximated by a network of widely varying tunnel conductances and the film conductivity can be described in terms of percolation theory. We demonstrate that the expected exponential decrease of the conductivity with increasing length of linker molecules is weakened by the presence of high conductance percolation pathways and we show that due to three-dimensional current percolation the conductivity of the nanoparticle films becomes film thickness dependent.

A smart nanofibrous material for adsorbing and detecting elemental mercury in air

“…Their absorptive capacity was improved (700 ng cm −2 ) when the gold electrodes were made rough (more binding sites). However, additionally to the natural affinity of gold for mercury, the increased facility for producing and depositing nanoparticles with noble metals facilitated their use as possible sensors, especially in aqueous environments (Nolan and Lippard, 2008;Chemnasiri and Hernandez, 2012;Ratner and Mandler, 2015;Dong et al, 2015). James et al (2012) developed a highly sensitive chip working in an LSPR mode based on gold nanoparticles (5 nm diameter) to monitor Hg 0 vapors.…”

“…Moreover, the linearity of the I-V curve let us suppose that the sensing scaffold had a good adhesion to the metal electrodes. The electron conductivity has been assumed to occur according to the percolation model (Macagnano et al, 2017;Müller et al, 2003), since the titania at room temperature was expected to be an insulating matrix. When it is metal doped, the electron conductivity is ruled by thermally activated electron tunneling from one metal island (gold nanoparticles) to the other.…”

“…Mercury (Hg) is released into the atmosphere through human activities, predominantly fossil fuel combustion, and naturally, for example, from soil outgassing, volcanoes, and evasion from the sea (Pirrone et al, 2010;Pacyna et al, 2010). One of the more troublesome issues in recent years has been to quantify not only the strength of emission sources but also the effects of the re-emission of previously deposited Hg on the overall distribution, concentration, and speciation of Hg in the atmosphere (Hedgecock et al, 2003).…”

Formation of a rectifier with gold nanoclusters: X-ray reflectivity and atomic force microscopy measurements

“…Here we demonstrate that one can form MR using dodecanethiol capped gold nanocluster of 3.3 nm diameter by forming asymmetric spatial configuration ⎯ one side having thiol chain and the otherside silicon oxide and a fatty acid salt, gadolinium stearate. Although electrical properties of metal nanoclusters connected by organic tails are being studied rigorously [6][7][8][9], to the best of our knowledge the MR formation through spatial asymmetry in these well-studied Au nanocluster systems has not been reported earlier.…”

“…, L t =11Å and ε t =2.2, which is the commonly used [7] value for alkane chains, ε b comes out to be 3.3. The dielectric constant of the bottom barrier is expected to be higher than the top one because of the presence of SiO 2 .…”